The thing is, having alcoholism in your family also makes it more likely that you'll be in a relationship with one...it's what we know. The crucial thing here is that your son is now growing up in that same situation and getting the same training...you know you want better for him. Being physically abusive to you is a deal breaker, not just for you but for your child.
You can't fix your husband's addiction, only he can and it has to come from him. Stick around and read a few stories here...so many good people lose decades of their lives getting ever more tangled up in their loved one's addiction until they're just as sick as they are.
You are financially independent and clearly a smart person. Take that child and get on with a better life.
Sending you a hug.